The invention relates to a drive device, for a movable part, in particular a hinged side window of a vehicle, with an actuating drive which is connected to the movable part via connecting elements.
U.S. Pat. No. 4,186,524 discloses a drive device for a hinged side window of a vehicle. This hinged side window is arranged in an articulated manner on a chassis (for example, the B-pillar) of the vehicle and can be brought by an actuating drive out of its closed position into the open position and back again or into intermediate positions.
The actuating drive is designed as an electric motor which acts on the threaded rod via gearwheels, the threaded rod being connected to a Bowden cable. As a result of the rotation of the threaded rod, the Bowden cable is moved linearly and thus causes the hinged side window to be opened or closed.
The disadvantage of this arrangement is that it is complicated, since the actuating drive has to be arranged in a region which is far removed from the point at which the connecting element engages on the hinged side window. This results in a high outlay in terms of assembly.
It would be conceivable, then, to shift the actuating drive directly into the region in which the connecting element is fastened to the hinged side window. Here too, however, just as in the embodiment according to U.S. Pat. No. 4,186,524, there is the problem that drive devices produced in large series and therefore having tolerances generate noise, particularly when the hinged side window is opened, since the connecting element is fastened to the hinged side window via a ball joint, in order to make it possible for the end of the connecting element to follow an arcuate path of movement. Since such a ball joint and also the connecting element are subject to tolerances, wind flows and vehicle vibrations also result in noise-generating oscillations of the hinged side window which are transmitted to the drive device, generate noises there and are disturbing to the vehicle occupants. Such noises are disturbing particularly because they occur in a region where the occupant""s head is located.
The object on which the invention is based is, therefore, to improve the drive device for a movable part, in particular a hinged side window of a vehicle, in such a way that oscillations of the components involved are largely prevented or ruled out completely.
According to the invention, provision is made for designing individual flights of at least one threaded piece in such a way that they come to bear under the effective force in the respectively associated flights of the other threaded piece. Individual threaded pieces are usually produced from plastic by the injection molding method, this method being subject to certain tolerances. The invention now makes use of the fact that individual flights of one threaded piece are designed, for example, to be thicker than the remaining flights, whilst the flights of the other threaded piece have a uniform shape and uniform dimensions. What is achieved thereby is that the thicker individual flights come to bear under the effective force in the respectively associated flights of the other threaded piece, so that the tolerances occurring during production are therefore compensated and sluggishness which is still permitted, and which can be overcome easily by the actuating drive, is taken into account, in order thereby effectively to prevent the tendency to oscillation. Advantageously, not all the flights of the threaded piece are designed, for example, to be thicker, since inadmissible and also unnecessary sluggishness would be obtained as a result. It is therefore sufficient that only individual flights (such as, for example, every second or every fifth flight and so on) may be designed differently from the remaining flights. It is important that there is always at least one flight (spindle tooth) in the thread.
In a development of the invention, individual flights are designed to be curved in the circumferential direction with respect to the remaining flights. In this case, the curve may be a simple curve, but also an extremely elongated S-curve, so that the flanks of the individual flights come to bear partially, under the effective force, on the flights of the associated threaded piece. Again, by this means too, the necessary slight sluggishness is achieved, so that tolerances can be compensated.
In a development of the invention, individual flights at least partially have a slot in the circumferential direction. These individual flights are then, again, designed to be thicker than the remaining flights, some resilience being achieved by means of the slot, since the flanks of a flight which are separated from one another by the slot press against the flight of the associated threaded piece.
In a further refinement of the invention, individual flights are arranged in a position deviating from the position predetermined by the associated threaded piece. This offset out of the desired position in the circumferential direction likewise causes a flank of a flight to press against the flank of the flight of the associated threaded piece, so that, here too, the effect that tolerances are compensated is achieved again.
It goes without saying that, where the threaded piece is concerned, the measures described can be taken individually or in combination with one another.
In a particularly advantageous way, a measure or a combination of measures is used in the case of a threaded piece which is designed as an external thread, since an external thread is produced in the injection molding method by means of a mold composed of two assembled and reseparable molds, whereas an internal thread is produced with a mold having an external thread, this core in the mold with an internal thread being turned out after the production process. If, however, the threaded piece with the internal thread is also produced from two or more mold halves which can be separated after production, the measures described are also used where this threaded piece is concerned.
Furthermore, as an additional measure for reducing undesirable noises, there is provision for a ball head mounted in a ball socket of the ball joint or for the ball socket to be provided with elastically resilient means. As a rule, the ball joint consists of plastic which is produced, for example, by the injection molding method. In this case, tolerances occur, so that the ball head mounted in the ball socket can still move with some play relative to the ball socket on account of these tolerances. These tolerances are eliminated by the elastically resilient means in a way according to the invention, so that, although the ball head can still move (if appropriate, somewhat sluggishly) in the ball socket, a positive connection has been made, so that there is no longer any space available for oscillations. Moreover, solid-borne sound from the actuating drive (motor noise) is thereby prevented from being transmitted to the hinged side window. Consequently, the source of origin of the disturbing oscillations described and therefore of the resulting generation of noise is eliminated. Also, these oscillations can no longer be transmitted in the direction of the actuating drive, so that the components involved here are likewise not excited to oscillate, with the result that the noise level is further reduced or noises are no longer generated at all and wear is markedly reduced.
In a development of the invention, the ball head has at least one peripheral groove which receives a rubber ring. Such a ball head can therefore be produced in a simple way, the peripheral groove either being introduced as early as during the production process or being introduced after the ball head has been produced. The rubber ring is, for example, a so-called O-ring which is available, cost-effectively and in a multiplicity of different dimensions (diameters and thicknesses). The drive device according to the invention can therefore also be produced cost-effectively.
In a development of the invention, the ball head has two parallel grooves which are arranged out of center and in each of which a rubber ring is inserted. Since there are therefore two peripheral faces available, with which the surface of the rubber ring can bear on the inner face of the ball socket, this ensures that, during every movement, always at least one surface of a rubber ring bears on the inner face of the ball socket and disturbing noises are therefore effectively avoided. This is necessary, in particular, when the ball joint executes a curved movement on its path of movement. A web occurring between the grooves serves for the transmission of force during tension and compression movements. The ball head may also consist of two ball head halves provided correspondingly with a groove. When the rubber rings are pressed together during tension and compression movements, the surfaces of the ball head halves serve for the transmission of force and come to bear positively on the ball socket.
In a development of the invention, the ball head is covered at least partially with an elastically resilient layer. Such an elastically resilient layer may be drawn on over the ball head, for example after it has been produced, and it is also conceivable for the ball head, by being dipped into an appropriate liquid, to be covered with such a layer which subsequently changes to a solid state. Such a layer also ensures that the tolerance between the ball socket and the ball head of the ball joint is eliminated.
The same effect is obtained even if or if only the ball socket is covered at least partially on its inside with an elastically resilient layer. It may also be mentioned that it is also conceivable for the inside of the ball socket to be provided with at least one peripheral groove, into which a rubber ring is inserted in each case, although it is expedient for these measures to be carried out only as far as the ball head is concerned, since the production and assembly operation is simpler in this case.
In a development of the invention, the ball joint is arranged between the connecting element and the movable part. The connecting element is, for example, the already known Bowden cable or a connecting rod or, if appropriate, a combination of the two elements mentioned. Since the hinged side window is arranged in an articulated manner on the chassis and the ball joint is arranged at a distance from this point of articulation, when the hinged side window is being moved from the close position into the open position the ball joint follows an approximately curved path which, by virtue of the ball joint, become possible even though the connecting element executes an essentially linear movement. That is to say, the end of the connecting element (connecting rod) describes a linear path of movement which is converted via the ball joint into a curved path of movement.
The same effect is obtained when the ball joint is arranged between the connecting element and the actuating drive. Depending on the length of the path of movement to be described, it is advantageous if a ball joint is arranged at both ends of the connecting element (connecting rod). Any desired path of movement and any length of the desired path of movement can consequently be implemented without difficulty. It goes without saying that the two ball joints at the respective end of the connecting element are provided with the elastically resilient means, as described above.